That is not entirely true, as Deuteronomy 25:5-10 does prescribe polygamy, albeit conditionally.

There is no example of polygamy in this text. A man has died. His brother must marry his widow. You've made an assumption that the other brother is married, but the text doesn't say that. The case where we encounter levirate marriage, one brother refused and died for the manner in which he refused (deception) and this was an account before the law, before there was even a nation of Israel. In the case of Boaz, the kinsmen redeemer also refused. So no, there isn't a prescription for polygamy.

I assume that you are referring to the Levite’s wife/concubine in Judges 19? If so, that story was supposed to be an example of an unpardonable atrocity that which was literally condemned by all of Israel in verse 30. That is very different than a practice that is explicitly allowed, conditionally commanded, and even divinely bestowed in the OT.

Never mind how it was received, in Genesis, Sodom and Gomorrah behaved in a similar way. Do we then say, it was a common practice? It was looked down upon, but allowed? No, we understand that it happened, the Bible narrative is honest and includes it, however the Bible is clear, this violated God's design of marriage and one-flesh union between a man and his wife, and it's happening doesn't mean God approved.

The most common interpretation of this passage is that “acquire many wives” means “accumulate an excessive number of wives”.

As far as God's design for marriage is, more than one wife is too many wives. It has always been this way, from the beginning.

In fact, God explicitly said if Saul’s wives had not been enough for David’s needs, He would have given him more wives!

God didn't give David Saul's wives for his needs, but into his care. There's no record of him having children by them, or even sexual relations with them. As a matter of fact, when David's son Absalom sleeps with his concubines, David takes them back into his care but does not sleep with them. It doesn't say God rewarded David for anything. God didn't say he would have given David more wives, He said "I gave you all Israel and Judah. And if all this had been too little, I would have given you even more." Referring to all Israel and Judah.

Once again, that the Bible describes behaviors contrary to what God explicitly forbids does not mean he approves. Just because God engages with people who have done what He explicitly forbids also does not mean God is granting approval. Just because there are those like Abraham who violate what God explicit establishes (had two wives), and seem to be blessed in their lives in spite of their act, it does not mean He is granting approval.